左房快速起搏对肺静脉口及心房肌电重构的影响

Electrical remodeling of atrium and pulmonary vein ostia after rapid left atrial pacing.

目的探讨左房快速起搏对肺静脉口、左右心耳电重构的影响。方法运用快速起搏左心耳的方法建立心房颤动(AF)模型,在起搏前及起搏后的第1,3,5,7d对左、右心耳;左上、左下肺静脉口;右上、右下肺静脉口的有效不应期(ERP)、ERP频率适应性、ERP离散度及心房间的传导时间进行测定。采用S1S2程序刺激,基础起搏周长(PCL)分别为400,300,200ms,S2为200ms,以5ms的步长递减。程序刺激结合Burst刺激对上述心房部位进行AF的诱发,记录AF的发生率。在第8天关闭起搏器,采用上述相同方法对起搏停止后即刻;2,4,6,24h的上述各部位的ERP进行测定。结果起搏1d后各个基础起搏周长下各部位的ERP明显缩短,ERP频率适应性降低,ERP离散度增大(P<0.05),而心房间传导时间无明显变化(P>0.05);起搏终止后各部位的ERP逐渐延长,但起搏终止后6hERP与快速起搏前相比仍有明显缩短(P<0.05);24h后ERP基本恢复到起搏前水平,两者相比无明显差异(p>0.05);随着起搏时间的延长各部位AF的诱发率逐渐增高(P<0.05)。结论快速心房起搏不仅引起心房肌电重构,亦引起肺静脉电重构。

Objective To study the effect of rapid left atrial pacing on electrical remodeling of atria and pulmonary vein ostia. Methods Atrial fibrillation（AF） models were prepared by pacing left auricle with a pacemaker in 13 goats. The ERPs of atria and pulmonary vein ostia, dispersion of ERP, rate-adaptation of ERP and interatrium conduction time were quantified before and after pacing for 1,3,5,7 days. The ERPs of above sites were measured by a decremental technique with 5-ms steps at pacing cycle lengths of 200 ms（PCL200）, 300ms（PCL300）, 400 ms PCL200） for 8 beats. AF was induced by programmable stimulation combined with burst stimulation, and inducibility of AF was observed. The ERPs of the above sites were determined at once, 2, 4, 6, 24 hours after AF stopping with identical program. Results After rapid left atrial pacing（3 000 beats/min）, the ERPs of left and right auricles, pulmonary vein ostia were significantly shorter than that before pacing, a markod increase in dispersion of ERP and decrease in rate adaptation of ERP were also observed （P〈0.05）. But intcratrium conduction time was not altered（ P 〉0. 05）. On the 8th day, pacemaker was turned off. The ERPs were still significantly short at once ,2, 4, 6 hours after stopping pacing（ P 〈 0.05 ）, and the ERPs returned to the level before pacing at 24 hours （p 〉 0.05 ）. The inducibility of AF of left and right auricles, pulmonary vein ostia increased with AT persistence（ P 〈 0.05 ）. Conclusion Rapid atrial pacing not only causes electrical remodeling of atrium, but also causes electrical remodeling of pulmonary veins.